Commit ebd4fd02 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Kaixiong Yu
Browse files

nilfs2: fix kernel bug due to missing clearing of buffer delay flag 

stable inclusion
from stable-v5.15.170
commit 822203f6355f4b322d21e7115419f6b98284be25
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB2BWP
CVE: CVE-2024-50116

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=822203f6355f4b322d21e7115419f6b98284be25



--------------------------------

commit 6ed469df0bfbef3e4b44fca954a781919db9f7ab upstream.

Syzbot reported that after nilfs2 reads a corrupted file system image
and degrades to read-only, the BUG_ON check for the buffer delay flag
in submit_bh_wbc() may fail, causing a kernel bug.

This is because the buffer delay flag is not cleared when clearing the
buffer state flags to discard a page/folio or a buffer head. So, fix
this.

This became necessary when the use of nilfs2's own page clear routine
was expanded.  This state inconsistency does not occur if the buffer
is written normally by log writing.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Link: https://lore.kernel.org/r/20241015213300.7114-1-konishi.ryusuke@gmail.com


Fixes: 8c26c4e2 ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Reported-by: default avatar <syzbot+985ada84bf055a575c07@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=985ada84bf055a575c07


Cc: stable@vger.kernel.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarKaixiong Yu <yukaixiong@huawei.com>
parent 929a9df3

fs/nilfs2/page.c

+4 −2
Original line number Diff line number Diff line
@@ -77,7 +77,8 @@ void nilfs_forget_buffer(struct buffer_head *bh) 
	const unsigned long clear_bits =

		(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |

		 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |

		 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));

		 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |

		 BIT(BH_Delay));



	lock_buffer(bh);

	set_mask_bits(&bh->b_state, clear_bits, 0);
@@ -410,7 +411,8 @@ void nilfs_clear_dirty_page(struct page *page, bool silent) 
		const unsigned long clear_bits =

			(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |

			 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |

			 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));

			 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |

			 BIT(BH_Delay));



		bh = head = page_buffers(page);

		do {